CN110908106A

CN110908106A - Optical device

Info

Publication number: CN110908106A
Application number: CN201910845871.6A
Authority: CN
Inventors: 太田健史; 生田凉
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2018-09-14
Filing date: 2019-09-09
Publication date: 2020-03-24
Also published as: TW202011076A; JP2020046455A; US20200088979A1

Abstract

The present invention relates to an optical device. In order to control the focal position of light at high speed and with high accuracy, an optical device includes: a first reflective surface 101 configured to be rotatable about a rotation axis 104 and to reflect light; a second reflecting surface 102 configured to be rotatable about a rotation axis 104, face the first reflecting surface 101, and reflect light from the first reflecting surface 101; a third reflective surface 114 that returns light from the second reflective surface 102 to the second reflective surface 102; and a control unit 120 configured to: the focal position in the optical axis direction of light returned from the third reflection surface 114 to the first reflection surface 101 via the second reflection surface 102 is controlled by rotating the first reflection surface 101 and the second reflection surface 102 about the rotation axis 104 in a state where the relative arrangement between the first reflection surface 101 and the second reflection surface 102 is maintained.

Description

Optical device

Technical Field

The invention relates to an optical device and a processing device.

Background

In various optical systems, one important factor in improving the characteristics of an optical device is to control the focal position of light at high speed and with high accuracy. For example, in an optical apparatus that performs work such as marking, piercing, and welding using laser light, controlling the focal position of light from a laser oscillator at high speed and with high accuracy contributes to improving the work quality.

The control of the focal position can be divided into two types of control in the optical axis direction and control in the direction perpendicular to the optical axis.

For example, the control of the focal position in the optical axis direction is performed by moving the position of the condenser lens in the optical system in the optical axis direction. However, since the condenser lens is heavy and is driven by the linear stage, it is difficult to move the condenser lens at high speed and with high accuracy.

For example, control of the focal position in the direction perpendicular to the optical axis is performed by using a so-called f θ lens and changing the angle of light incident on the f θ lens. However, the f θ lens has a problem that the beam diameter at the focal position varies depending on the angle.

Document 1(d.j.campbell, p.a.krug, i.s.falcon, l.c.robinson, and g.d.tait, "Rapid scan phase modulator for interferometric applications" Applied optics vol.20, Issue 2, pp.335 to 342(1981)) discloses a technique for rotating two facing mirrors, changing the optical path length, and changing the optical phase. However, the technique disclosed in document 1 is not related to the control of the focal position. Therefore, the optical device disclosed in document 1 does not include a non-collimating optical system that changes the beam diameter in the optical axis direction. In the document 1, since the problem of the deviation from the focal position does not occur, it is not easy to apply the technique disclosed in the document 1 to an optical apparatus that controls the focal position.

On the other hand, japanese unexamined patent publication No. 2016-103007 discloses a technique of moving an optical path of light for laser processing in a direction perpendicular to the optical path using a plurality of four fixed mirrors and one rotatable mirror. However, this technique has a problem in that since at least five mirrors are required, the weight of the optical device increases and the optical loss increases.

Further, document 2(Meng-Chang Hsieh, Jiun-You Lin and Chia-Ou Chang, "Using a Hexagonal Mirror for Varying Light Intensity in the Measurement of Small-Angle Variation" Sensors 2016,16,1301) discloses a technique of reflecting Light Using a hexagonal Mirror, regardless of the control of the focal position. A technique of moving an optical path of incident light in a direction perpendicular to the optical path using a refractive index medium is known. However, in this technique, optical loss increases due to the refractive index medium. Further, when a refractive index medium is used, the size of the refractive index medium must be large to achieve a large amount of movement. As a result, this technique is disadvantageous in terms of weight and high-speed movement.

Disclosure of Invention

An aspect of the present invention is to provide an optical apparatus that facilitates high-speed and high-precision control of the focal position of light.

According to an aspect of the present invention, an optical apparatus for controlling a focal position of light includes: a first reflective surface configured to be rotatable about a rotation axis and to reflect light; a second reflecting surface configured to be rotatable about the rotation axis, face the first reflecting surface, and reflect light from the first reflecting surface; a third reflective surface that returns light from the second reflective surface to the second reflective surface; and a control unit configured to: the focal position in the optical axis direction of light returned from the third reflection surface to the first reflection surface via the second reflection surface is controlled by rotating the first reflection surface and the second reflection surface around the rotation axis in a state where the relative arrangement between the first reflection surface and the second reflection surface is maintained.

Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

Fig. 1A to 1C are diagrams illustrating an optical apparatus including a focus position shifter in a first embodiment.

Fig. 2 is a diagram showing a principle of controlling the focal position in the optical axis direction in the first embodiment.

Fig. 3 is a diagram showing a second embodiment of the optical device.

Fig. 4 is a diagram showing a third embodiment of the optical apparatus.

Fig. 5 is a diagram showing a fourth embodiment of the optical apparatus.

Fig. 6 is a diagram showing a fifth embodiment of the optical apparatus.

Fig. 7 is a diagram showing a sixth embodiment of the optical apparatus.

Fig. 8 is a diagram showing a seventh embodiment of the optical apparatus.

Fig. 9 is a diagram showing an eighth embodiment of the optical apparatus.

Fig. 10 is a diagram showing a ninth embodiment of the optical apparatus.

Fig. 11A to 11E are diagrams illustrating a tenth embodiment of an optical apparatus.

Fig. 12 is a diagram showing a principle of controlling a focal position in a direction perpendicular to an optical axis in the tenth embodiment.

Fig. 13 is a diagram showing an eleventh embodiment of the optical device.

Fig. 14 is a diagram showing a twelfth embodiment of the optical device.

Fig. 15 is a diagram showing a thirteenth embodiment of the optical apparatus.

Fig. 16 is a diagram showing a fourteenth embodiment of the optical apparatus.

Fig. 17 is a diagram showing a fifteenth embodiment of the optical apparatus.

Fig. 18 is a diagram showing a sixteenth embodiment of the optical apparatus.

Fig. 19 is a diagram showing a seventeenth embodiment of an optical device.

Fig. 20 is a diagram showing an eighteenth embodiment of the optical device.

Fig. 21 is a diagram showing a nineteenth embodiment of the optical apparatus.

Fig. 22 is a diagram showing an example of a processing device using one of the embodiments of the optical device.

Detailed Description

(first embodiment)

Hereinafter, a first embodiment for implementing the present invention will be described with reference to the drawings.

In the drawings, the same reference numerals are given to the same members and elements, and the repetitive description will be omitted. In the following description, a direction in which the optical axis extends is referred to as an optical axis direction. In an optical apparatus to be described below, a focal position shifter is used to control the focal position of light at high speed and with high accuracy. That is, the optical device controls the focal position of the light emitted from the focal position shifter in the optical axis direction and the focal position in the direction perpendicular to the optical axis of the light.

First, a technique of controlling the focus position in the optical axis direction using the focus position mover according to the first embodiment will be described.

Fig. 1A to 1C are diagrams illustrating a first embodiment of an optical device including a focus position shifter.

Fig. 1A shows an example in which the optical axis of light incident from the light source 300 to the focus position shifter 100 and the optical axis of light emitted from the focus position shifter 100 in the downward direction of the drawing are in different directions. Here, the direction is different in the sense that the optical axis of the light emitted from the focus position shifter 100 has a slope equal to or greater than 45 ° and equal to or less than 135 ° (e.g., an angle of 90 °) with respect to the optical axis of the light incident on the focus position shifter 100.

Fig. 1B shows an example in which the optical axis of light incident on the focus position shifter 200 and the optical axis of light exiting from the focus position shifter 200 are the same direction. Here, the same direction means that the optical axis of the light emitted from the focus position shifter 200 is in a range equal to or greater than 0 ° (parallel) and less than 45 ° with respect to the optical axis of the light incident on the focus position shifter 200.

Fig. 1C shows a comparative example. In the comparative example, as shown by X in the drawing, the focal positions FP _ h0, FP _ h1, and FP _ h2 in the optical axis direction are controlled by moving the position of the condenser lens 118 in the optical axis direction. However, in such a configuration, since the condenser lens 118 is heavy and is driven by a linear stage, it is difficult to move the condenser lens 118 at high speed and with high accuracy.

In contrast, the

focus position movers

100 and 200 shown in fig. 1A and 1B each control the focus positions FP _ h0, FP _ h1, and FP _ h2 in the optical axis direction by controlling the optical path length of light without driving the condenser lens.

For example, light from the light source 300 enters the

focus position shifter

100 or 200 via the non-collimating optical system 400. Here, the non-collimating optical system is an optical system that changes collimated light (parallel light) from the light source 300 into non-collimated light (convergent light or diffuse light) whose beam diameter changes as the light propagates in the optical axis direction. In this example, the non-collimating optical system 400 includes the condensing lens 117 shown in fig. 2 that generates the condensing light, but the present invention is not limited thereto, and a diffraction grating or a concave (or convex) mirror may be used. The light source 300 is, for example, a laser oscillator, and the light from the light source 300 is, for example, a laser beam.

The light emitted from the

focus position shifter

100 or 200 is focused at a predetermined position via the optical system 500 that forms a focus. The optical system 500 is, for example, a condensing optical system that condenses the light emitted from the

focus position shifter

100 or 200. Although the optical system 500 is not necessary, the optical system 500 has the following advantages because the optical system 500 is provided.

In this example, the

focus position shifter

100 or 200 changes the focus position of the light emitted from the

focus position shifter

100 or 200 by changing the optical path length of the light incident from the non-collimating optical system 400. In this case, since a light spot is formed during the light traveling inside the

focus position shifter

100 or 200, the light from the condenser lens 117 may be changed from the convergent light to the divergent light in some cases. In these cases, the optical system 500 is required, and the optical system 500 again condenses the diffused light emitted from the

focus position shifter

100 or 200 to form condensed light.

That is, when the optical system 500 performs control of the focal position in the optical axis direction by controlling the optical path length using the

focal position shifter

100 or 200, the optical system 500 has an advantage of reliably forming the focal point of the light emitted from the

focal position shifter

100 or 200.

The focus position shifter 100 performs control of the focus position in the optical axis direction. The focus position shifter 100 controls the focus position of the light emitted from the focus position shifter 100 in the optical axis direction by changing the optical path length of the light incident from the non-collimating optical system 400.

Thus, the focus position shifter 100 includes the first reflection surface 101, the second reflection surface 102 facing the first reflection surface 101, the third reflection surface 114 that returns light, the fourth reflection surface 115 that extracts light, and the control unit 120.

The first, second, third and fourth reflecting

surfaces

101, 102, 114 and 115 are mirrors, for example. Here, the fourth reflecting surface 115 has a characteristic of transmitting light from the non-collimating optical system 400 and reflecting light from the first reflecting surface 101. In this example, for convenience, it is assumed that the first and second reflection surfaces 101 and 102 are parallel to each other. However, the first and second reflection surfaces 101 and 102 may not be parallel to each other as long as the first and second reflection surfaces 101 and 102 face each other.

Here, if the angle α formed between the first and second reflection surfaces 101 and 102 is in the range of equal to or greater than 0 ° (parallel) and less than 90 °, it is considered that the first and second reflection surfaces 101 and 102 face each other because it is necessary to be able to reflect light from the first reflection surface 101 through the second reflection surface 102, as will be described below.

The first reflective surface 101 and the second reflective surface 102 are configured to rotate together about an axis of rotation 104. The first reflecting surface 101 and the second reflecting surface 102 must be rotated together around the rotation axis 104 in a state where the relative arrangement (relative angle and relative position) between the first reflecting surface 101 and the second reflecting surface 102 is maintained. Thus, the focus position mover 100 includes, for example, a stage 103 that is rotatable about a rotation axis 104. In this case, the first and second reflecting

surfaces

101 and 102 are fixed to the stage 103. The control unit 120 changes the optical path length of the light incident from the non-collimating optical system 400 by changing the rotation angle of the stage 103, and controls the focal position of the light emitted from the focal position shifter 100 in the optical axis direction.

The rotation axis 104 may be located in a region between the first and second reflection surfaces 101 and 102, or may be located in a region other than the region between the first and second reflection surfaces 101 and 102, as will be described below.

The first reflective surface 101 reflects light from the non-collimating optical system 400. The light reflected from the first reflecting surface 101 travels toward the second reflecting surface 102 and is reflected by the second reflecting surface 102. The third reflective surface 114 returns light from the second reflective surface 102 to the second reflective surface 102. That is, light from the non-collimating optical system 400 that passes through the optical path 109, the optical path 110, and the optical path 111 in this order is returned by the third reflecting surface 114. The light returned by the third reflecting surface 114 is reflected by the fourth reflecting surface 115 via the same optical path (i.e., the optical path 111, the optical path 110, and the optical path 109) in order to exit.

By using the focus position shifter 100, and controlling, for example, the rotation angle of the stage 103 by the control unit 120, the optical path length of the light within the focus position shifter 100 can be changed. Therefore, the focal position of the light 122 emitted from the focal position shifter 100 in the optical axis direction can be controlled.

The change in the optical path length in the focus position shifter 100 will be described.

In the following description, it is assumed that the center point of the condenser lens 117 is the incident point 112 of light, where (x)_i,y_i) Is the coordinates of the incident point 112. Assume that a point on the third reflecting surface 114 that reflects light from the second reflecting surface 102 is an intermediate point 113, where (x)_o,y_o) Is the coordinate of the intermediate point 113. Further, it is assumed that a point at which the light returned from the third reflection surface 114 is emitted is the emission point 112', and that an optical path length from the incident point 112 to the intermediate point 113 is the same as an optical path length from the intermediate point 113 to the emission point 112'.

In addition, (x)₀₁,y₀₁) Is the coordinate of the intersection 105 of the first reflecting surface 101 and a vertical line drawn from the rotation axis 104 to the first reflecting surface 101, and(x₀₂,y₀₂) Is the coordinate of the intersection 106 of the second reflecting surface 102 and a perpendicular line drawn from the rotation axis 104 to the second reflecting surface 102. It is assumed that the length R of a vertical line drawn from the rotation axis 104 to the first reflecting surface 101 is the same as the length R of a vertical line drawn from the rotation axis 104 to the second reflecting surface 102. That is, it is assumed that the distance between the first reflecting surface 101 and the second reflecting surface 102 is 2R.

When a vertical line is drawn from the rotation axis 104 to the optical path (incident optical axis) 109, the length of the vertical line is assumed to be Y. That is, light incident on the non-collimating optical system 400 is incident on the first reflective surface 101 at an offset distance Y from the rotational axis 104. A state where the first reflection surface 101 is parallel to the optical path (incident optical axis) 109 is defined as a rotation angle of 0 °. Here, at the rotation angle of 0 °, it is assumed that the first reflection surface 101 is closer to the optical path (incident optical axis) 109 than the second reflection surface 102.

When the state of the rotation angle of 0 ° is set as the reference, it is assumed that the stage 103 is rotated counterclockwise by the angle θ from the rotation angle of 0 °. The rotation angle θ is controlled to be in the range of, for example, 0 ° to 90 °. Therefore, the motor that rotates the gantry 103 is preferably a current motor (galvano-motor) that can rotate the gantry 103 counterclockwise or clockwise. Here, the motor that rotates the stage 103 may be a rotation motor that may rotate the stage 103 only in a single direction (e.g., counterclockwise). In this case, when the rotation angle θ is decreased, the rotation angle θ may be controlled again from a state of rotating by 0 ° after one rotation of the stage 103.

Under the above-mentioned premise, first, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) As shown in the following formulas (1) to (4).

...(1)

...(2)

...(3)

...(4)

Next, when (x)₁，y₁) Is a coordinate on the first reflecting surface 101 and (x)₂，y₂) Is the coordinate on the second reflecting surface 102, the relationships shown in the following equations (5) and (6) can be obtained.

y₁-y₀₁＝(tanθ)×(x₁-x₀₁)

...(5)

y₂-y₀₂＝(tanθ)×(x₂-x₀₂)

...(6)

Next, (x)_m1，y_m1) Is the coordinate of point 107 on the first reflective surface 101 that reflects light from the non-collimating optical system 400, and (x)_m2，y_m2) Is the coordinate of a point 108 on the second reflective surface 102 that reflects light from the first reflective surface 101. y is_B1The y coordinate on the optical path 109 between the non-collimating optical system 400 and the first reflective surface 101, and (x)_BR，y_BR) Is a coordinate on the optical path 110 between the first reflective surface 101 and the second reflective surface 102. In this case, the coordinates on the optical path 110 between the first reflecting surface 101 and the second reflecting surface 102 may be as shown in the following equation (7).

y_BR-y_m1＝tan(2θ)×(x_BR-x_m1)

...(7)

Next, y_BOIs the y coordinate on the optical path 111 of the light reflected by the second reflective surface 102. In this case, the coordinates (x) of the reflection point 107_m1，y_m1) And the coordinates (x) of reflection point 108_m2，y_m2) As shown in the following formulas (8) to (11).

...(8)

y_m1＝Y

...(9)

...(10)

...(11)

Next, when (x)_i，y_i) Is the coordinate of the point of incidence 112 of the light and (x)_o，y_o) Is the coordinate of the light's midpoint 113, the length of the optical path 109, i.e., from the coordinate (x)_i，y_i) To the coordinate (x)_m1，y_m1) The length of (d) is as shown in the following formula (12).

...(12)

The length of the optical path 110, i.e. from the coordinate (x)_m1,y_m1) To the coordinate (x)_m2,y_m2) The length of (d) is represented by the following formula (13).

...(13)

Further, the length of the optical path 111, i.e., from the coordinate (x)_m2,y_m2) To the coordinate (x)_o,y_o) The length of (d) is represented by the following formula (14).

...(14)

Thus, the optical path length from the point of incidence 112 to the midpoint 113 of the light, i.e., from the coordinate (x)_i,y_i) To the coordinate (x)_o,y_o) The length of (d) is represented by the following formula (15).

l＝4R·sinθ-x_i+x_o

...(15)

Here, it is assumed that the light from the second reflecting surface 102 returns to the second reflecting surface 102 again through the third reflecting surface 114 without moving the optical axis. In this case, since the optical path length from the incident point 112 to the midpoint 113 is equal to the optical path length from the midpoint 113 to the exit point 112', the optical path length from the incident point 112 to the exit point 112' is as shown in the following formula (16).

2×l＝8×R·sinθ-x_i+2×x_o+Δ

...(16)

Here, Δ is a moving amount of the optical axis in the third reflecting surface 114. As described above, when it is assumed that there is no optical axis movement in the third reflecting surface 114, Δ is zero.

As is clear from equation (16), the optical path length changes according to the rotation angle θ of the stage 103. That is, by controlling the rotation angle θ, it is possible to control the optical path length of the light in the focus position shifter 100 and control the focus position of the light emitted from the focus position shifter 100 in the optical axis direction. When the distance (2 × R) between the first reflecting surface 101 and the second reflecting surface 102 is set large, the amount of change in the optical path length with respect to the rotation angle θ can be set large.

For example, by rotationally driving the stage 103 using a current motor, the focal position of light in the optical axis direction can be controlled at a higher speed and with higher accuracy than when the condenser lens 117 is linearly driven. The size of the first reflecting surface 101 and the size of the second reflecting surface 102 may be the same or may be different from each other. In the latter case, the first reflecting surface 101 is preferably smaller in size than the second reflecting surface 102, as will be described below.

In the foregoing description, it is assumed that the first reflecting surface 101 and the second reflecting surface 102 are parallel to each other, but the above principle can be applied even when the first reflecting surface 101 and the second reflecting surface 102 are not parallel to each other.

For example, when it is assumed that the first reflecting surface 101 deviates from the second reflecting surface 102 by an angle α, the optical axis of the light along the optical path 111 deviates from the optical axis of the light along the optical path 109 (2 × α). however, since the optical axis of the light along the optical path 111 does not depend on the rotation angle θ, the light from the second reflecting surface 102 moves in parallel despite the change in the rotation angle θ. that is, even when the rotation angle θ changes, the relationship in which the optical axis of the light along the optical path 111 deviates from the optical axis of the light along the optical path 109 (2 × α) is constant.

This means that the above principle can be applied even when the first and second reflecting

surfaces

101 and 102 are not parallel to each other. In other words, this means that even if it is assumed that the first reflecting surface 101 and the second reflecting surface 102 are parallel to each other, the parallelism may not be accurately set. Depending on the reflection angle at which light is reflected by the third reflecting surface 114, a change in parallelism at the reflection positions of the first and second reflecting

surfaces

101 and 102 can be compensated for.

(second embodiment)

Fig. 3 is a diagram showing a second embodiment as a specific example of the optical device 200 in fig. 1B.

This embodiment explains an example of the optical path when the rotation angle θ of the stage 103 is changed in units of 1 ° in the range of 56 ° to 63 °.

First reflective surfaces 1011, a. The first reflection surface 1011 and the second reflection surface 1021 correspond to the case of the rotation angle θ of 56 °, and are disposed parallel to each other. The first and second reflecting

surfaces

1012 and 1022 correspond to the case of the rotation angle θ of 59 ° and are disposed parallel to each other. The first reflecting surface 1013 and the second reflecting surface 1023 correspond to the case of the rotation angle θ of 63 ° and are disposed parallel to each other.

The first

reflective surfaces

1011, and 1013 have the same size as the second reflective surfaces 1021, and are, for example, 120 mm. In this example, it is assumed that the dimensions of the first reflective surfaces 1011, ·...., 1012, ·.... and 1013 and the dimensions of the second reflective surfaces 1021,..., 1022,... and 1023 are dimensions (widths) in a direction parallel to the upper surface of the gantry 103.

Here, the optical axis direction of light along the optical path 109 is referred to as x-axis, and the direction perpendicular thereto is referred to as y-axis. The condenser lens 117 is disposed at a position of 10mm in the x direction and-5 mm in the y direction from the rotation axis 104. The third reflecting surface 114 is disposed at a position 20mm in the x direction from the rotational axis 104. The third reflecting surface 114 is, for example, a mirror having two reflecting surfaces perpendicular to each other. That is, light from the second

reflective surfaces

1021, and 1023 is reflected from one of the two reflective surfaces and then reflected by the other of the two reflective surfaces. Thereafter, the light returns from the third reflective surface 114 to the second

reflective surfaces

1021, 1022, 1023.

As described above, when the third reflection surface 114 is a mirror having two reflection surfaces perpendicular to each other, the

optical paths

109, 110, and 111 serving as the forward path may be slightly deviated from the

optical paths

111, 110, and 109 serving as the return path. Therefore, there is no fear of interference between light propagating along the

optical paths

109, 110, and 111 serving as the forward paths and light propagating along the

optical paths

111, 110, and 109 serving as the return paths. Here, in this case, since Δ of equation (16) is not zero, Δ at the focal position in the optical axis direction needs to be considered.

Instead of a mirror having two reflecting surfaces, the third reflecting surface 114 may be one mirror that reflects light to the same optical path as that of the incident light.

The fourth

reflective surfaces

1151 and 1152 extract the exit light 122 in the same direction as the optical axis of the incident light on the optical path 109 (i.e., x direction). Here, the fourth

reflective surfaces

1151 and 1152 may be disposed to extract the outgoing light 122 in a direction (for example, y direction) intersecting the optical axis of the incident light on the optical path 109.

Collimated light is incident on the condenser lens 117 from the light source 300, and the focal length of the condenser lens 117 is 200 mm. The stage 103 is driven by a current motor, and the rotation angle θ is controlled in a range of 56 ° to 63 °. In the figure, the optical paths are shown at intervals of 1 ° so that the optical paths are easily seen. The rotational speed of the gantry 103 through the current motor may be set to about 1 revolution per second (1Hz — 1 rps).

Under the aforementioned conditions, the optical path length may vary in the range of 151.5mm to 156.5 mm. The moving speed of the focal position when the rotation angle θ is changed from 59 ° to 62 ° is 5mm/(3/360) ═ 600 mm/ms. In the case of the related art in which the focus is moved by the linear movement of the lens disposed on the linear stage, the moving speed of the focus position is about 200 mm/ms. That is, according to this example, the focal position can be controlled at high speed and with high accuracy.

In this example, the fourth reflecting surface 1151 is provided at a position 10mm in the x direction from the condenser lens 117, and the fourth reflecting surface 1152 is provided at a position-10 mm in the x direction from the fourth reflecting surface 1151. This is a design for preventing the optical path of light extracted from the focus position mover 200 from interfering with the first reflective surfaces 1011, ·. Since the focal length of the condenser lens 117 is 200mm, the focal point is formed at a position of about 45mm to 50mm in the x direction from the fourth reflecting surface 1152.

According to the second embodiment, by controlling the optical path length in this way, the focal position of light in the optical axis direction can be controlled at high speed and with high accuracy.

When one mirror is used as the third reflecting surface 114 and the third reflecting surface 114 reflects light to the same optical path as the incident light, it is preferable to insert a beam splitter immediately before the first reflecting surfaces 1011, the.

Light from the non-collimating optical system 400 may be converted into a linearly polarized light beam by the wavelength plate, may be converted into a circularly polarized light beam by the polarizing beam splitter and the quarter wavelength plate, and may then be incident on the first reflective surfaces 1011, the. In this case, by converting the light returned from the third reflecting surface 114 into a linearly polarized light beam whose polarization is rotated again by 90 ° by the quarter-wave plate, the linearly polarized light beam can be extracted by the polarization beam splitter.

The stage 103 is a disk, but may be a part of a disk, a rod-like shape, or any other shape in view of weight reduction or the like. Here, in any shape, it is necessary to implement a structure in which the rotation shaft 104 is physically connected to the first reflection surface 1011, the.

(third embodiment)

Fig. 4 is a diagram showing a third embodiment as a specific example of the optical apparatus in fig. 1A to 1C.

As described above, the size of the first reflective surface 101 may be different from the size of the second reflective surface 102. Therefore, in this example, an example will be described in which the size of the first reflection surface 101 is set smaller than that of the second reflection surface 102 and the weight of the stage 103 driven by a current motor is reduced, for example.

In this case, since the load on the current motor is reduced, the stage 103 can be rotated at a high speed. This means that the focus position shifter 100 can control the focus position at high speed and with high accuracy.

Coordinate x indicated in formula (8)_m1The following formula is obtained for the rotation angle θ minute.

...(17)。

When equation (17) is at the central angle theta of the controllable rotation angle theta₀When it is 0, x_m1Is minimal. Therefore, the relational expression shown in expression (18) can be obtained.

...(18)

Therefore, when θ is equal to θ₀In this case, the coordinate (x) of the intersection 105 of a vertical line drawn from the rotation axis 104 to the plane including the first reflection surface 101 and the plane₀₁,y₀₁) And coordinates (x) of point 107_m1,y_m1) In line, incident light is reflected from the first reflective surface 101 at point 107. In this case, it is not necessary to increase the size of the first reflection surface 101 to cover x_m1Displacement of (2). That is, by making the size of the first reflecting surface 101 smaller than that of the second reflecting surface 102, the weight of the stage 103 can be reduced. Due to the coordinates (x) of the intersection 105₀₁,y₀₁) And when theta is equal to theta₀Coordinates (x) of the reflection point 107 at_m1,y_m1) And so the center of gravity on the stage 103 is easily stabilized, which also contributes to high-speed control of the focal position.

The configuration of the optical device in this example is substantially the same as that of the first embodiment. Here, the condenser lens 117 is disposed at a position of-10 mm in the x direction and-12.3 mm in the y direction from the rotation axis 104 so that the formula (17) is at θ₀Becomes 0 at 60.5 °. As a result, the size (width) of the first reflection surface 101 may be set to 4mm and the size of the second reflection surface 102 may be set to 13mm in a direction parallel to the upper surface of the stage 103.

In this example, a length R1 of a vertical line drawn from the rotation axis 104 to a plane including the first reflection surface 101 is different from a length R2 of a vertical line drawn from the rotation axis 104 to the second reflection surface 102. In this case, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) As shown in the following formulas (19) to (22).

...(19)

...(20)

...(21)

...(22)

In this case, the optical path length is as follows.

2×l＝4×(R₁+R₂)·sinθ-x_i+2×x_o+Δ

...(23)

When equation (16) is compared with equation (23), it is understood that the change in the optical path length does not depend on the distance from the rotation axis 104, but on the distance (2R or R1+ R2) between the first and second reflection surfaces 101 and 102. In this example, as described above, the size of the second reflecting surface 102 is larger than the size of the first reflecting surface 101. Therefore, in this example, the second reflecting surface 102 is disposed at a position closer to the rotation axis 104 than the first reflecting surface 101.

As described above, according to the third embodiment, the load on the current motor is reduced. Therefore, the stage 103 can be rotated at high speed, and the focus position mover 100 controls the focus position at high speed and with high accuracy.

(fourth embodiment)

Fig. 5 is a diagram showing a fourth embodiment as a specific example of the optical apparatus in fig. 1.

The fourth embodiment is an example in which the first reflecting surface 101 and the second reflecting surface 102 are not disposed in point symmetry with respect to the rotational axis 104.

In this example, the length of a vertical line drawn from the rotation axis 104 to the first reflection surface 101 or a plane including the first reflection surface 101 is set to 50 mm. The length of a vertical line drawn from the rotation axis 104 to the second reflection surface 102 or a plane including the second reflection surface 102 is set to 0 mm. That is, the rotation axis 104 is included in the second reflection surface 102 or a plane including the second reflection surface 102. The condenser lens 117 is disposed at a position 40mm in the x direction and-25 mm in the y direction from the rotation axis 104. In addition, a third reflecting surface 114 for the returning light is provided at a position of 30mm in the x direction from the rotation axis 104.

The control unit 120 rotationally drives the stage 103 by the current motor. The control unit 120 controls the rotation angle of the stage 103 in the range of 59 ° to 62 °. The rotation speed of the stage 103 by the current motor is set to, for example, about 1 revolution per second (1Hz ═ 1 rps).

Under the above conditions, the optical path length may vary in the range of 151.5mm to 156.5 mm. For example, when the rotation angle θ is 59 °, light is reflected from the first and second reflecting

surfaces

1014 and 1024, and the optical path length is 156.5 mm. When the rotation angle θ is 62 °, the light is reflected by the first reflecting surface 1015 and the second reflecting surface 1025, and the optical path length is 151.5 mm.

In this example, the focal point position can be controlled at high speed and with high accuracy, and the size of the first reflection surface 101 and the size of the second reflection surface 102 can be reduced. For example, the size (horizontal width) of the first reflection surface 101 may be set to 4mm, and the size (horizontal width) of the second reflection surface 102 may be set to 13 mm.

(fifth embodiment)

Fig. 6 is a diagram showing a fifth embodiment as a specific example of the optical apparatus in fig. 1.

The fifth embodiment is an example in which light from the non-collimating optical system 400 is reflected multiple times by the first reflecting surface 101 and the second reflecting surface 102.

In this example, by changing the configuration in which the distance between the first and second reflection surfaces 101 and 102 is close or the area of the first reflection surface 101 facing the second reflection surface 102 is increased, the number of times light is reflected between the first and second reflection surfaces 101 and 102 can be increased.

For example, in the figure, light is reflected twice by the first and second

reflective surfaces

101 and 102 along a forward path to the third reflective surface, and twice from the first and second

reflective surfaces

101 and 102 along a return path from the third reflective surface 114. In the first to fourth embodiments described above, the number of times light is reflected by the first and second reflecting

surfaces

101 and 102 along the forward and return paths is only once. That is, according to this example, the optical path length can be increased by about two times as compared with the first to fourth embodiments described above.

This means that when the variation range of the optical path length is constant, the range of the rotation angle θ of the stage 103 can be further reduced in this example as compared with the first to fourth embodiments described above. That is, in this example, since a desired optical path length can be obtained from a small rotation angle θ, it is possible to contribute to high-speed and high-precision control of the focal position.

In this example, since the distance between the first reflection surface 101 and the second reflection surface 102 is narrow and the first reflection surface 101 and the second reflection surface 102 are disposed at positions close to the rotation shaft 104, the load of the motor can be reduced, thereby achieving high-speed operation.

The number of times light is reflected between the first and second reflection surfaces 101 and 102 is not limited to 2, and may be 3 or more.

(sixth embodiment)

Fig. 7 is a diagram showing a sixth embodiment as a specific example of the optical apparatus in fig. 1.

The sixth embodiment is an example in which light reciprocates a plurality of times along the forward path and the return path in the first to fourth embodiments described above. Thus, the optical apparatus according to this example includes a plurality of return reflecting surfaces that return light.

For example, in this example, a first retro-reflective surface 1141, a second retro-reflective surface 1142, and a third retro-reflective surface 1143 are included. The first return reflective surface 1141 is equivalent to the third reflective surface 114 in the first to fifth embodiments described above. The second retro-reflection surface 1142 functions as a fifth reflection surface that returns the light returned by the first retro-reflection surface 1141 and reflected by the first reflection surface 101 to the first reflection surface 101. The third retro-reflection surface 1143 functions as a sixth reflection surface that returns the light returned by the second retro-reflection surface 1142 and reflected by the second reflection surface 102 to the second reflection surface 102.

Each of the first, second, and third retro-

reflective surfaces

1141, 1142, 1143 is a mirror having two perpendicular reflective surfaces. Therefore, the optical path of the incident light incident on each of the retro-reflective surfaces and the reflected light reflected from each of the retro-reflective surfaces can be shifted. That is, light may reciprocate multiple times between the first retro-reflective surface 1141, the second retro-reflective surface 1142, and the third retro-reflective surface 1143.

In this example, the direction in which the light is displaced by the first, second, and third return

reflective surfaces

1141, 1142, and 1143 is a direction perpendicular to the upper surface of the stage 103, but the present invention is not limited thereto. For example, the direction in which the light is displaced by the first, second, and third return

reflective surfaces

1141, 1142, and 1143 may be a direction parallel to the upper surface of the stage 103.

In the above configuration, the motor 130 such as a current motor rotationally drives the stage 103 to set the rotation angle θ of the stage 103. Thereafter, the light from the non-collimating optical system 400 reciprocates twice between the first return reflecting surface 1141, the second return reflecting surface 1142, and the third return reflecting surface 1143, and is then extracted by the fourth reflecting surface 115.

According to this example, the optical path length can be increased as in the fifth embodiment. Therefore, a desired optical path length can be obtained from a small rotation angle θ. As a result, the focal position can be controlled at high speed and with high accuracy. The distance between the first reflecting surface 101 and the second reflecting surface 102 is narrow, and the first reflecting surface 101 and the second reflecting surface 102 are disposed at positions close to the rotating shaft 104, so that the load on the motor can be reduced, thereby achieving high-speed operation.

The number of times light reciprocates between the plurality of return reflecting surfaces is not limited to 2, and may be 3 or more.

(seventh embodiment)

Fig. 8 is a diagram showing a seventh embodiment as a specific example of the optical apparatus in fig. 1.

The seventh embodiment relates to the configuration of the first reflecting surface 101 and the second reflecting surface 102. In the first to sixth embodiments described above, the first reflecting surface 101 and the second reflecting surface 102 are, for example, mirrors independent of each other. However, the first and second reflection surfaces 101 and 102 are not limited thereto, and may be inner surfaces of a predetermined member.

For example, as shown, the first reflective surface 101 and the second reflective surface 102 may be crystalline surfaces of one crystal (e.g., a glass material). That is, the crystal 140 has therein the first reflecting surface 101 and the second reflecting surface 102. The crystal 140 is fixed to the stage 103.

In this example, the parallelism of the first and second reflecting

surfaces

101 and 102 can be improved by a polishing work on the crystal 140. That is, when the first and second reflection surfaces 101 and 102 are independent mirrors and each mirror is fixed to the stage 103, it is necessary to adjust the parallelism of the first and second reflection surfaces 101 and 102, and thus the work may be complicated. Therefore, when the crystal 140 is used, work for ensuring parallelism of the first and second reflecting

surfaces

101 and 102 and work for mounting the first and second reflecting

surfaces

101 and 102 on the stage 103 can be performed, respectively.

Therefore, according to this example, work for assembling the optical device can be efficiently performed.

When the crystal 140 is used as the first and second reflecting

surfaces

101 and 102, it is preferable to coat the end surface S on which light is incident_inAnd an end surface S from which light exits_outTo reduce reflection of light.

The crystal 140 is preferably arranged such that the optical axis of the light on the

optical paths

109 and 111 and the end face S_inAnd S_outThe angle formed between them is the so-called brewster angle. The brewster angle depends on the material of crystal 140 and is, for example, about 60 °. In this case, the optical axis of light on the optical path 109 and the end surface S are set by about 60 °_inAngle formed therebetween andoptical axis and end surface S of light on optical path 111_outEach of the angles formed therebetween, the end surface S can be reduced_inAnd S_outReflection loss in the optical waveguide.

(eighth embodiment)

Fig. 9 is a diagram showing an eighth embodiment as a specific example of the optical apparatus in fig. 1.

The eighth embodiment is an example of such a case: in the course of the light propagating inside the focus position shifter 100, a spot of the condensed light from the condenser lens 117 is formed, and the light exits from the focus position shifter 100 as diffused light. In this case, the diffused light emitted from the focus position shifter 100 is changed to convergent light by the optical system 400', so that the spot of the light is restricted again.

The optical system 400' is a converging optical system that converges the beam diameter of light in the propagation direction of light. Optical system 400' includes, for example,

condenser lenses

150 and 160. A spot of the outgoing light 122 extracted from the fourth reflective surface 115 is formed after the outgoing light 122 passes through the

condenser lenses

150 and 160.

Here, a is a distance from a spot position formed inside the focus position shifter 100 by the condenser lens 117 to the condenser lens 150, and b is a distance from the condenser lens 150 to a spot position of light condensed by the condenser lens 150. Further, f is the focal length of the condenser lens 150. At this time, a > f is satisfied.

The following relationship holds.

...(24)

Therefore, the optical path length is controlled using the focus position shifter 100, that is, the distance b can be controlled by controlling the distance a.

In this example, by providing the optical system 400', it is possible to cause the focus position shifter 100 to control the focus position and set the focus position at a position relatively distant from the focus position shifter 100. Therefore, it is possible to improve the degree of freedom of the focal position in the optical axis direction, and to provide a device such as a galvano mirror for controlling the direction of the outgoing light 122 inside the optical system 400' (the focal position in the direction perpendicular to the optical axis).

In the foregoing configuration, for example, collimated light (parallel light) is incident on the condenser lens 117. The focal length of the condenser lens 117 is, for example, 50 mm. In this example, the length of a vertical line drawn from the rotation axis 104 to the first reflection surface 101 or a plane including the first reflection surface 101 is set to 20 mm. The length of a vertical line drawn from the rotation axis 104 to the second reflection surface 102 or a plane including the second reflection surface 102 is set to 0 mm. That is, the rotation axis 104 is included in the second reflection surface 102 or a plane including the second reflection surface 102.

The rotation angle θ of the stage 103 is controlled to be in the range of 38 ° to 43 °. Fig. 9 shows that the light paths are changed at intervals of 1 ° so that the light paths are easily seen. The condenser lens 117 is disposed at positions 5mm in the x direction and-15 mm in the y direction from the rotation axis 104. The third reflecting surface 114 is disposed at a position of 25mm in the x direction. In this case, the optical path length of the outgoing light 122 reflected from the condenser lens 117 by the third reflecting surface 114 and emitted from the focus position shifter 100 can be controlled in the range of about 89.3mm to 94.6 mm.

The outgoing light 122 extracted through the fourth reflective surface 115 is incident on the condenser lens 150 within the optical system 400'. When the distance from the fourth reflecting surface 114 to the condenser lens 150 is about 10.5mm, the optical path length from the incident point 112 to the exit point 112' can be controlled to be in the range of 94.8mm to 100.1 mm.

When it is assumed that the focal length f of the condenser lens 150 is 15mm, the focal point on the exit side can be controlled in the range of 22.5mm to 21.4 mm. The condenser lens 160 is disposed at a position 50mm from the condenser lens 150. In this case, when it is assumed that the focal length of the condenser lens 160 is 20mm, a focal point is formed at a position 73.3mm to 66.7mm from the condenser lens 160.

In this example, one condenser lens 117 is used in the non-collimating optical system 400, and two

condenser lenses

150 and 160 are used in the converging optical system 400'. Here, the number of lenses used in the optical device in this example is not limited to 3. For example, the number of lenses may also be increased or decreased according to the focal position (design value). An optical design can be realized that controls the focal position while converging light at a desired numerical aperture NA. Further, the lenses included in the non-collimating optical system 400 and the condensing optical system 400' are not limited to convex lenses, and may be concave lenses, cylindrical lenses, or the like.

(ninth embodiment)

Fig. 10 is a diagram showing a ninth embodiment as a specific example of the optical apparatus in fig. 1.

The ninth embodiment is an example of a case where the first reflecting surface 101 and the second reflecting surface 102 are not parallel to each other. Here, although the first and second reflection surfaces 101 and 102 are described as being non-parallel, the first and second reflection surfaces 101 and 102 must face each other. That is, in this arrangement, light from the first reflective surface 101 may be reflected by the second reflective surface 102.

For example, the angle α formed between the first reflective surfaces 101(1016 and 1017) and the second reflective surfaces 102(1026 and 1027) is about 60 °. the first reflective surface 1016 and the second reflective surface 1026 correspond to the case where the rotation angle θ is 56 °, and the first reflective surface 1017 and the second reflective surface 1027 correspond to the case where the rotation angle θ is 63 °.

R1 is the length of a vertical line drawn from the rotation axis 104 to the first reflection surface 101 or a plane including the first reflection surface 101, and R2 is the length of a vertical line drawn from the rotation axis 104 to the second reflection surface 102 or a plane including the second reflection surface 102. In this case, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) The following formulae (25) to (28).

...(25)

...(26)

...(27)

...(28)

When (x)₁，y₁) Is a coordinate on the first reflecting surface 101 and (x)₂，y₂) Are coordinates on the second reflecting surface 102, these coordinates are described in the following equations (29) and (30).

y₁-y₀₁＝(tanθ)×(x₁-x₀₁)

...(29)

y₂-y₀₂＝(tan(θ+α))×(x₂-x₀₂)

...(30)

Here, (x)_m1，y_m1) Is the point at which light from the non-collimating optical system 400 is reflected by the first reflective surface 101, and (x)_m2，y_m2) Is the point at which light is reflected by the second reflective surface 102. In addition, y_BIIs the y coordinate on optical path 109, and (x)_BR，y_BR) Is a coordinate on the optical path 110 between the first reflective surface 101 and the second reflective surface 102. In this case, the coordinates on the optical path 110 between the first reflecting surface 101 and the second reflecting surface 102 can be described in equation (31).

y_BR-y_m1＝tan(2θ)×(x_BR-x_m1)

...(31)

In addition, when (x)_o，y_o) Being the coordinates on the optical path 111 between the second reflecting surface 102 and the third reflecting surface 114, the coordinates on the optical path 111 can be described in equation (32).

y_o-y_m2＝tan(2α)×(x_O-x_m2)

...(32)

As understood from the above, the amount of change in the optical path length does not depend on the distances R1 and R2 between the rotation axis 104 and the first and second reflection surfaces 101 and 102, but depends on the distance (R1+ R2) between the first and second reflection surfaces 101 and 102. That is, when the distance between the first reflection surface 101 and the second reflection surface 102 is shortened, the optical path length can be reduced. In contrast, when the distance between the first reflection surface 101 and the second reflection surface 102 is extended, the optical path length can be increased.

In the foregoing configuration, for example, collimated light (parallel light) is incident on the condenser lens 117 having a focal length of 100mm, the rotation angle θ of the stage 103 is controlled in the range of 56 ° to 63 °, the first reflection surface 101 is disposed at a position 50mm (R1 ═ 50) from the rotation axis 104, and the second reflection surface 102 is disposed at a position 0mm (R2 ═ 0) from the rotation axis 104, the second reflection surface 102 is inclined α ═ 60 ° with respect to the first reflection surface 101.

The condenser lens 117 is disposed at positions of 30mm in the x direction and-25.7 mm in the y direction from the rotation axis 104 the third reflection surface 114 has a layout in which light is reflected at a position of 30mm in the x direction from the rotation axis 104 when the rotation angle θ is 56 °, the third reflection surface 114 is inclined by 2 α (═ 120 °) with respect to the y axis so that the optical path of the reflected light overlaps with the optical path of the incident light.

The third reflective surface 114 may have a layout such that the optical path of the reflected light does not overlap with the optical path of the incident light. For example, the third reflecting surface 114 may include two reflecting surfaces perpendicular to each other such that the optical path of the reflected light is slightly deviated from the optical path of the incident light in the z direction (i.e., a direction perpendicular to the upper surface of the stage 103). The third reflective surface 114 may be slightly inclined in the z-direction so that the optical path of the reflected light does not overlap with the optical path of the incident light.

In the foregoing configuration, the optical path length may vary in the range of 45.2mm to 51.4 mm. That is, by controlling the rotation angle θ of the stage 103, a variation of 6.2mm can be realized as the optical path length. When it is assumed that the fourth reflecting surface 115 is disposed at a position 5mm away from the end of incident light, the focal position can be controlled within a range of 59.8mm to 53.6mm from the fourth reflecting surface 115.

When the first and second reflection surfaces 101 and 102 are parallel to each other, the optical path length can be controlled in a range of, for example, 82.9mm to 89.1 mm. That is, in this case, the amount of change in the optical path length is 6.2mm and is constant in this example. However, when the first and second reflection surfaces 101 and 102 are parallel to each other, the optical path length required to achieve this variation is about 90mm longer than in this example. Therefore, a design such as an increase in the focal length of the condenser lens is required.

However, in this example, since a predetermined amount of change can be obtained with a short optical path length, the focal position in the optical axis direction can be controlled without a design in which the focal length of the condenser lens is increased.

In this example, the layout of the second reflective surface 102 may be decided such that the reflection of light by the second reflective surface 102 occurs closer to the rotation axis 104. In this case, the load on the current motor is reduced, and therefore the focal position can be controlled at high speed.

(tenth embodiment)

Next, a technique of controlling a focus position in a direction perpendicular to the optical axis using the focus position mover according to the tenth embodiment will be described.

Fig. 11A to 11E are diagrams illustrating an example of an optical device including a focus position shifter according to a tenth embodiment.

Fig. 11A shows an example in which the optical axis direction of light incident on the focus position shifter 600 is different from the optical axis direction of light emitted from the focus position shifter 600. Here, the different directions mean that the optical axis of the light emitted from the focus position shifter 600 has an inclination equal to or greater than 45 ° and equal to or less than 135 ° (for example, an inclination of 90 °) with respect to the optical axis of the light incident on the focus position shifter 600.

Fig. 11B shows an example in which the optical axis direction of light incident on the focus position shifter 700 is the same as the optical axis direction of light emitted from the focus position shifter 700. Here, the same direction means that the optical axis of the light emitted from the focus position shifter 700 is in a range equal to or greater than 0 ° (parallel) and less than 45 ° with respect to the optical axis of the light incident on the focus position shifter 700.

Fig. 11C shows a combination example of the focus position shifter 600 in fig. 11A and the focus position shifter 700 in fig. 11B.

Fig. 11D and 11E show comparative examples. In the comparative example, the focus positions FP _ h0, FP _ h1, and FP _ h2 in the direction perpendicular to the optical axis were controlled using the current scanner 800 including a so-called f θ lens. However, the optical axes of the light emitted from the current scanner 800 depend on the focus positions FP _ h0, FP _ h1, and FP _ h2 and are not parallel to each other. Therefore, the beam diameters at the focus positions FP _ h0, FP _ h1, and FP _ h2 change according to the focus position.

The

focus position shifters

600 and 700 shown in fig. 11A and 11B change the positions at which light exits from the

focus position shifters

600 and 700 according to the focus positions FP _ h0, FP _ h1, and FP _ h 2. Therefore, the optical axes of the light emitted from the

focus position shifters

600 and 700 do not depend on the focus positions FP _ h0, FP _ h1, and FP _ h2 and are parallel to each other. Therefore, the beam diameters at the focus positions FP _ h0, FP _ h1, and FP _ h2 do not change, and the focus position in the direction perpendicular to the optical axis can be controlled.

For example, light from the light source 300 is incident on the

focus position shifters

600 and 700 in a state where the light from the light source 300 is, for example, collimated light (parallel light). The

focus position shifters

600 and 700 perform control such that the optical path of light emitted from each focus position shifter is moved in a direction perpendicular to the optical path. Then, the light emitted from the

focus position shifters

600 and 700 is changed into convergent light by the non-collimating optical system 400.

Here, in this embodiment, the non-collimating optical system 400 that generates converging light to form a focal point is disposed on the rear stage of the

focal position shifters

600 and 700. This is because the focal position in the optical axis direction may be changed simultaneously due to a change in the optical path length when the focal position (exit position) is controlled in the direction perpendicular to the optical axis using non-collimated light.

That is, the object of this embodiment is to independently control the focal position (exit position) in the direction perpendicular to the optical axis of light. Therefore, it is preferable that collimated light is incident on the

focus position shifters

600 and 700, and light exiting from the

focus position shifters

600 and 700 becomes convergent light in the non-collimating optical system 400.

An exception is a case where the control of the focal position in the optical axis direction of the light and the control of the focal position in the direction perpendicular to the optical axis of the light are preferably performed simultaneously using one of the

focal position shifters

600 and 700.

The light source 300 is, for example, a laser oscillator, and the light from the light source 300 is, for example, a laser beam.

The optical axes of the light emitted from the

focus position shifters

600 and 700 do not depend on the focus positions FP _ h0, FP _ h1, and FP _ h2 and are parallel to each other. This is because, as the following principle will be described, the focal position in the direction perpendicular to the optical axis is not controlled by the f θ lens, but is controlled by controlling the rotation angles of the first and second reflecting surfaces that face each other and are rotatable about the rotation axis.

The focus position in the direction perpendicular to the optical axis is controlled by the focus position shifter 700. The focus position shifter 700 controls the focus position in the direction perpendicular to the optical axis of the light emitted from the focus position shifter 700 by shifting the optical path of the light incident from the non-collimating optical system 400.

Accordingly, the focus position shifter 700 includes the first reflective surface 101, the second reflective surface 102 facing the first reflective surface 101, and the control unit 120.

The first and second

reflective surfaces

101 and 102 are mirrors, for example. In this example, for convenience of description, it is assumed that the first reflection surface 101 and the second reflection surface 102 are parallel to each other. However, the first and second reflection surfaces 101 and 102 may not be parallel to each other as long as the first and second reflection surfaces 101 and 102 face each other.

Here, the fact that the first and second reflecting

surfaces

101 and 102 face each other means that the angle α between the first and second reflecting

surfaces

101 and 102 is in the range of equal to or greater than 0 ° (parallel) and less than 90 °. this is because it is important that the second reflecting surface 102 is able to reflect light from the first reflecting surface 101, as will be described below.

Both the first reflective surface 101 and the second reflective surface 102 are rotatable around an axis of rotation 104. The first reflecting surface 101 and the second reflecting surface 102 must be rotated about the rotational axis 104 in a state where the relative arrangement between the first reflecting surface 101 and the second reflecting surface 102 is maintained. Accordingly, the focus position shifter 700 includes, for example, the stage 103 that is rotatable about the rotation axis 104. In this case, the first and second reflecting

surfaces

101 and 102 are fixed to the stage 103. The control unit 120 moves the optical path of light incident on the non-collimating optical system 400 by changing the rotation angle of the stage 103, and controls the focal position of light emitted from the focal position shifter 100 in the direction perpendicular to the optical axis.

As will be described below, the rotation axis 104 may be located in a region between the first and second reflection surfaces 101 and 102, or may be located in a region other than the region between the first and second reflection surfaces 101 and 102.

The first reflective surface 101 reflects light from the non-collimating optical system 400. The light reflected by the first reflecting surface 101 travels toward the second reflecting surface 102 and is reflected by the second reflecting surface 102. That is, light from the non-collimating optical system 400 is output to the exit point 112' via the

optical paths

109, 110, and 111 in order.

When the focus position shifter 700 is used, for example, the control unit 120 may change the emission position of the light emitted from the focus position shifter 700 by controlling the rotation angle of the stage 103. Therefore, the focal position of the outgoing light 122 emitted from the focal position shifter 700 in the direction perpendicular to the optical axis can be controlled.

The movement of the optical path inside the focus position shifter 700 will be described.

In the following description, the center point of the lens 117' is the point of incidence 112 of the light,and (x)_i,y_i) Is the coordinates of the incident point 112. In addition, (x)_o,y_o) Is the coordinates of the exit point 112', the light from the second reflective surface 102 exits at the exit point 112'.

In addition, (x)₀₁,y₀₁) Is the coordinate of the intersection 105 between the first reflecting surface 101 and a vertical line drawn from the rotation axis 104 to the first reflecting surface 101, and (x)₀₂,y₀₂) Is the coordinate of the intersection 106 between the second reflecting surface 102 and a perpendicular line drawn from the rotation axis 104 to the second reflecting surface 102. It is assumed that the length R of a vertical line drawn from the rotation axis 104 to the first reflecting surface 101 is the same as the length R of a vertical line drawn from the rotation axis 104 to the second reflecting surface 102. That is, it is assumed that the interval between the first reflecting surface 101 and the second reflecting surface 102 is 2R.

When a vertical line is drawn from the rotation axis 104 to the optical path (incident optical axis) 109, the length of the vertical line is assumed to be Y. That is, light incident on the non-collimating optical system 400 is incident on the first reflecting surface 101 offset from the rotational axis 104 by a distance Y. A state where the first reflection surface 101 is parallel to the optical path (incident optical axis) 109 is defined as a rotation angle of 0 °. Here, at the rotation angle of 0 °, it is assumed that the first reflection surface 101 is closer to the optical path (incident optical axis) 109 than the second reflection surface 102.

When the state of the rotation angle of 0 ° is set as the reference, it is assumed that the stage 103 is rotated counterclockwise by the angle θ from the rotation angle of 0 °. The rotation angle θ is controlled to be in the range of, for example, 0 ° to 90 °. Thus, the motor that rotates the gantry 103 is preferably a current motor that can rotate the gantry 103 counterclockwise or clockwise. Here, the motor that rotates the stage 103 may be a rotation motor that can rotate the stage 103 only in one direction (e.g., counterclockwise direction). In this case, when the rotation angle θ is set small, the rotation angle θ can be controlled again from the state of rotating by 0 ° by rotating the stage 103 once.

Under the above-mentioned premise, first, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) As shown in the following formulas (33) to (36).

...(33)

...(34)

...(35)

...(36)

Next, when (x)₁，y₁) Is a coordinate on the first reflecting surface 101 and (x)₂，y₂) Is the coordinate on the second reflecting surface 102, the relationship shown in the following equations (37) and (38) can be obtained.

y₁-y₀₁＝(tanθ)×(x₁-x₀₁)

...(37)

y₂-y₀₂＝(tanθ)×(x₂-x₀₂)

...(38)

Next, (x)_m1，y_m1) Is the coordinate of point 107 on the first reflective surface 101 that reflects light from the non-collimating optical system 400, and (x)_m2，y_m2) Is the coordinate of a point 108 on the second reflective surface 102 that reflects light from the first reflective surface 101. Suppose y_B1The y coordinate on the optical path 109 between the non-collimating optical system 400 and the first reflective surface 101, and (x)_BR，y_BR) Is a coordinate on the optical path 110 between the first reflective surface 101 and the second reflective surface 102. In this case, the coordinates on the optical path 110 between the first reflecting surface 101 and the second reflecting surface 102 can be described in the following equation (39).

y_BR-y_m1＝tan(2θ)×(x_BR-x_m1)

...(39)

Next, y_BOIs the y coordinate on the optical path 111 of the light reflected by the second reflective surface 102. In this case, the coordinates (x) of the reflection point 107_m1，y_m1) And the coordinates (x) of reflection point 108_m2，y_m2) Represented by the following formulae (40) to (43).

...(40)

y_m1＝Y

...(41)

...(42)

...(43)

Here, since the first and second reflection surfaces 101 and 102 are parallel to each other, the light from the second reflection surface 102 follows an optical path 111 parallel to the optical path 109 (i.e., where y is equal to y)_m2Upper optical path) and output to the exit point 112'. As shown in equation (43), it can be understood that the y-coordinate is changed by changing the rotation angle θ of the stage 103. By changing the distance R from the rotation axis 104 to the first reflection point 101 and the distance R from the rotation axis 104 to the second reflection point 102, the amount of movement can be increased.

Therefore, according to the foregoing principle, it is possible to control the emission position of light emitted from the focus position shifter 700 according to the rotation angle θ, and control the focus position in the direction perpendicular to the optical axis of the light.

In the foregoing description, it is assumed that the first and second reflection surfaces 101 and 102 are parallel to each other, but the above principle can be applied even when both the first and second reflection surfaces 101 and 102 are not parallel to each other.

For example, when it is assumed that the first reflective surface 101 is offset from the second reflective surface 102 by an angle α, the optical axis of the light along the optical path 111 is offset from the optical axis of the light along the optical path 109 (2 × α). however, since the optical axis of the light along the optical path 111 does not depend on the rotation angle θ, the light from the second reflective surface 102 is only translated despite the change in the rotation angle θ. that is, even when the rotation angle θ is changed, the relationship in which the optical axis of the light along the optical path 111 is offset from the optical axis of the light along the optical path 109 (2 × α) is constant.

surfaces

101 and 102 are not parallel to each other. In other words, this means that even when it is assumed that the first reflection surface 101 and the second reflection surface 102 are parallel to each other, the parallelism may not be accurately set. The optical system installed after the exit point 112' can compensate for the change in parallelism according to the reflection positions of the first and second reflection surfaces 101 and 102.

(eleventh embodiment)

Fig. 13 is a diagram illustrating an eleventh embodiment, which is a specific example of the optical device in fig. 11A to 11E.

This example is an example of an optical path when the rotation angle θ of the stage 103 is changed in units of 1 ° in the range of 82 ° to 86 °.

The first reflective surfaces 1011'. · and 1012' are disposed at positions 25mm from the rotation axis 104 (coordinates (0,0)), and the second reflective surfaces 1021'... and 1022' are also disposed at positions 25mm from the rotation axis (104). The first reflection surface 1011 'and the second reflection surface 1021' correspond to the case of the rotation angle θ of 82 °, and are disposed parallel to each other. The first and second reflecting surfaces 1012 'and 1022' correspond to the case of the rotation angle θ of 86 ° and are disposed parallel to each other.

The dimensions of the first reflective surfaces 1011' ·. In this example, it is assumed that the dimensions of the first reflective surfaces 1011 'and 1012' and the dimensions of the second reflective surfaces 1021 'and 1022' are dimensions (horizontal widths) in a direction parallel to the upper surface of the gantry 103. Here, the optical axis direction of light along the optical path 109 is referred to as x-axis, and the direction perpendicular thereto is referred to as y-axis. The condenser lens 117' is disposed at a position of-5 mm in the y direction (lower side in the figure) from the rotation axis 104.

Collimated light is incident on the lens 117 'from the light source 300, and the focal length of the condenser lens 117' is 200 mm. The stage 103 is driven by a current motor, and the rotation angle θ is controlled in a range of 82 ° to 86 °. The rotational speed of the gantry 103 through the current motor may be set to about 1 revolution per second (1Hz — 1 rps).

Under the above conditions, the exit position of the light from the focus position shifter 700 (i.e., the y-coordinate of the exit point 112') varies within a range from y0(═ 8.92mm) to y4(═ 3.72 mm). Here, y0 is the emission position at the rotation angle θ of 82 °, and y4 is the emission position at the rotation angle θ of 86 °. This means that the focus position mover 700 in this example can control the focus (y-coordinate) in the direction perpendicular to the optical axis in the range of 8.92mm to 3.72 mm. Further, the optical path (optical axis) 111 of the light emitted from the focus position shifter 700 in this example does not depend on the rotation angle θ and is parallel. This means that the beam diameter at the focal point does not change at each exit position.

According to this example, the speed of the light beam movement is 5mm/(4/360) ═ 450mm/ms in the range of the rotation angle θ from 82 ° to 86 °. That is, according to this example, the focal position can be controlled at high speed and with high accuracy.

However, in the comparative example, the number of times light is reflected is 6 in the ring mover disclosed in patent document 1. In the focus position shifter 700 according to this example, the number of times light is reflected is 2. This means that the focal position can be controlled in a state where the focal position shifter 700 according to this example sufficiently suppresses optical loss on the reflection surface.

In this example, the stage 103 is a disk, but may be a part of a disk, a rod-like shape, or any other shape in view of weight reduction or the like. Here, in any shape, it is necessary to realize a structure in which the rotation shaft 104 is physically connected to the first reflective surfaces 1011'. and 1012' and the second reflective surfaces 1021'. and 1022'.

(twelfth embodiment)

Fig. 14 is a diagram showing a twelfth embodiment, which is a specific example of the optical device in fig. 11A to 11E.

In this case, since the load on the current motor is reduced, the stage 103 can be rotated at a high speed. This means that the focus position shifter 700 can control the focus position at high speed and with high accuracy.

Coordinate x indicated in equation (44)_m1The following formula is obtained for the rotation angle θ minute.

...(44)

When equation (44) is at the central angle theta of the controllable rotation angle theta₀When it is 0, x_m1Is minimal. Therefore, the relational expression shown in expression (45) can be obtained.

...(45)

Therefore, when θ is equal to θ₀In this case, the coordinate (x) of the intersection 105 of a vertical line drawn from the rotation axis 104 to the plane including the first reflection surface 101 and the plane₀₁,y₀₁) And coordinates (x) of point 107_m1,y_m1) In line, incident light is reflected from the first reflective surface 101 at point 107. In this case, it is not necessary to increase the size of the first reflection surface 101 to cover x_m1Displacement of (2). That is, by making the scale of the first reflecting surface 101The size of the second reflecting surface 102 is smaller, so that the weight of the stage 103 can be reduced. Due to the coordinates (x) of the intersection 105₀₁,y₀₁) And when theta is equal to theta₀Coordinates (x) of the reflection point 107 at_m1,y_m1) And so the center of gravity on the stage 103 is easily stabilized, which also contributes to high-speed control of the focal position.

The configuration of the optical device in this example is substantially the same as that of the tenth embodiment in fig. 12. Here, the condenser lens 117 is disposed at a position of-2.13 mm in the y direction from the rotation axis 104 so that the expression (44) is at θ₀When 84 °, the temperature becomes 0. As a result, the size (horizontal width) of the first reflection surface 101 may be set to 2mm and the size of the second reflection surface 102 may be set to 8mm in a direction parallel to the upper surface of the stage 103.

In this example, a length R1 of a vertical line drawn from the rotation axis 104 to a plane including the first reflection surface 101 is different from a length R2 of a vertical line drawn from the rotation axis 104 to the second reflection surface 102. In this case, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) As shown in the following formulas (46) to (49).

...(46)

...(47)

...(48)

...(49)

In this case, the exit position (i.e., the exit point 11)2' y coordinate (y)_m2) The following).

...(50)

When equation (43) is compared with equation (50), it is understood that the variation of the exit position does not depend on the distance from the rotation axis 104 but on the distance (2R or R1+ R2) between the first and second reflection surfaces 101 and 102. In this example, as described above, the size of the second reflecting surface 102 is larger than the size of the first reflecting surface 101. Therefore, in this example, the second reflecting surface 102 is disposed at a position closer to the rotation axis 104 than the first reflecting surface 101.

As described above, according to the twelfth embodiment, the load on the current motor is reduced. Therefore, the stage 103 can be rotated at high speed, and the focus position mover 100 controls the focus position at high speed and with high accuracy.

(thirteenth embodiment)

Fig. 15 is a diagram showing a thirteenth embodiment, which is a specific example of the optical device in fig. 11A to 11E.

The thirteenth embodiment is an example in which the first reflecting surface 101 and the second reflecting surface 102 are not disposed in point symmetry with respect to the rotational axis 104.

In this example, the length of a vertical line drawn from the rotation axis 104 to the first reflection surface 101 or a plane including the first reflection surface 101 is set to 50 mm. The length of a vertical line drawn from the rotation axis 104 to the second reflection surface 102 or a plane including the second reflection surface 102 is set to 0 mm. That is, the rotation axis 104 is included in the second reflection surface 102 or a plane including the second reflection surface 102. The condenser lens 117' is disposed at a position of-25 mm in the y direction from the rotation axis 104. Further, the size (horizontal width) of the first reflection surface 101 is set to 6mm, and the size (horizontal width) of the second reflection surface 102 is set to 10 mm.

The control unit 120 rotationally drives the stage 103 by the current motor. The control unit 120 controls the rotation angle of the gantry 103 within a range of 82 ° to 86 °. The rotation speed of the stage 103 by the current motor is set to, for example, about 1 revolution per second (1Hz ═ 1 rps).

Under the above conditions, the exit position of the light from the focus position shifter 700 (i.e., the y-coordinate of the exit point 112') varies within a range from y0(═ 8.92mm) to y4(═ 3.72 mm). This means that the focus position mover 700 in this example can control the focus (y-coordinate) in the direction perpendicular to the optical axis in the range of 8.92mm to 3.72 mm. Further, the optical path (optical axis) 111 of the light emitted from the focus position shifter 700 in this example does not depend on the rotation angle θ and is parallel. This means that the beam diameter at each focal point does not change at each exit position.

(fourteenth embodiment)

Fig. 16 is a diagram showing a fourteenth embodiment, which is a specific example of the optical device in fig. 11A to 11E.

The fourteenth embodiment is an example in which light from the non-collimating optical system 400 is reflected multiple times by the first reflecting surface 101 and the second reflecting surface 102.

For example, in the figure, light is reflected twice by the first and second reflecting

surfaces

101 and 102. In the first to thirteenth embodiments described above, the number of times light is reflected by the first and second reflecting

surfaces

101 and 102 is only once. That is, according to this example, the moving amount of the exit position can be increased almost doubly as compared with the first to thirteenth embodiments described above.

This means that when the moving amount of the exit position is constant, the range of the rotation angle θ of the stage 103 can be further reduced in this example as compared with the first to thirteenth embodiments described above. That is, in this example, since the emission position can be moved by only a required movement amount according to a small rotation angle θ, it is possible to contribute to high-speed and high-precision control of the focus position.

(fifteenth embodiment)

Fig. 17 is a diagram illustrating a fifteenth embodiment, which is a specific example of the optical apparatus in fig. 11A to 11E.

The fifteenth embodiment is an example in which a third reflection surface 1144 that returns light from the second reflection surface 102 to the second reflection surface 102 is further provided in the above-described tenth to fourteenth embodiments. In this case, the light from the incident point 112 is reflected by the third reflective surface 1144 and returns along substantially the same path to propagate to the exit point 112'. That is, the incident point 112 and the exit point 112' of the light are located at substantially the same position.

The third reflecting surface 1144 is, for example, a mirror having two perpendicular reflecting surfaces. Accordingly, the optical paths of the incident light incident on the third reflection surface 1144 and the reflected light reflected by the third reflection surface 1144 may be shifted. In this example, the direction in which the light is displaced by the third reflection surface 1144 is a direction parallel to the upper surface of the stage 103, but the present invention is not limited thereto. For example, the direction in which the light is displaced by the third reflection surface 1144 may be a direction perpendicular to the upper surface of the stage 103, as will be described in a nineteenth embodiment to be described below.

Thus, when the light is returned only once using the third reflection surface 1144, the amount of movement of the exit position is almost doubled. When the moving amount of the exit position is constant, in this example, the range of the rotation angle θ of the stage 103 can be set small, and the load on the current motor can be reduced. That is, in this example, as in the fourteenth embodiment, since the emission position can be moved by a required movement amount according to a small rotation angle θ, the focus position can be controlled at high speed and with high accuracy.

In this example, when the direction in which light travels toward the third reflective surface 1144 is set as a forward path and the direction in which light returns from the third reflective surface 1144 is set as a return path, the light may reciprocate a plurality of times along the forward path and the return path. In this case, a new reflection surface of the return light may also be provided on the incident point 112 side.

(sixteenth embodiment)

Fig. 18 is a diagram showing a sixteenth embodiment, which is a specific example of the optical device in fig. 11A to 11E.

The sixteenth embodiment is an example in which a third reflection surface 1145 that returns light from the second reflection surface 102 to the second reflection surface 102 is further provided in the above-described tenth to fourteenth embodiments. In this case, the light from the incident point 112 is reflected by the third reflective surface 1145 and returns along substantially the same path to propagate to the exit point 112'. That is, the incident point 112 and the exit point 112' of the light are located at substantially the same position.

The third reflective surface 1145 is, for example, a flat mirror. However, a vertical line of the surface of the third reflection surface 1145 is not parallel to the optical path (optical axis) 111 of the light from the second reflection surface 102 and is inclined at a constant angle. Accordingly, the optical paths of the incident light incident on the third reflection surface 1145 and the reflected light reflected by the third reflection surface 1145 may be shifted.

The direction in which the light is displaced by the third reflection surface 1145 may be a direction parallel to the upper surface of the stage 103 as shown in the drawing, or alternatively may be a direction perpendicular to the upper surface of the stage 103. The direction in which the light is displaced by the third reflective surface 1145 may be an oblique direction that is not parallel or perpendicular to the upper surface of the stage 103.

For example, when the light is displaced in a direction parallel to the upper surface of the stage 103, the surface of the third reflective surface 1145 may be tilted by a predetermined amount in an x-y direction parallel to the upper surface of the stage 103 with respect to the optical path 111. When the light is displaced in a direction perpendicular to the upper surface of the stage 103, the surface of the third reflection surface 1145 may be tilted by a predetermined amount in a z-direction perpendicular to the upper surface of the stage 103 with respect to the optical path 111.

Thus, when the light is returned only once using the third reflection surface 1145, the amount of movement of the exit position is almost doubled. When the moving amount of the exit position is constant, in this example, the range of the rotation angle θ of the stage 103 can be set small, and the load on the current motor can be reduced. That is, in this example, as in the fourteenth embodiment, since the emission position can be moved by a required movement amount at a small rotation angle θ, the focus position can be controlled at high speed and with high accuracy.

In this example, when the direction in which light travels toward the third reflective surface 1145 is set as a forward path and the direction in which light returns from the third reflective surface 1145 is set as a return path, the light may reciprocate a plurality of times along the forward path and the return path. In this case, a new reflection surface of the return light may also be provided on the incident point 112 side.

(seventeenth embodiment)

Fig. 19 is a diagram showing a seventeenth embodiment as a specific example of an optical apparatus.

The seventeenth embodiment relates to the configuration of the first reflecting surface 101 and the second reflecting surface 102. In the tenth to sixteenth embodiments described above, the first and second reflecting

surfaces

101 and 102 are, for example, mirrors independent of each other. However, the first and second reflection surfaces 101 and 102 are not limited thereto, and may be inner surfaces of a predetermined member.

In this example, the parallelism of the first and second reflecting

surfaces

101 and 102 and work for mounting the first and second reflecting

surfaces

101 and 102 on the stage 103 can be performed, respectively.

When the crystal 140 is used as the first and second reflecting

surfaces

optical paths

109 and 111 and the end face S_inAnd S_outThe angle formed between them is the so-called brewster angle. The brewster angle depends on the material of crystal 140 and is, for example, about 60 °. In this case, the optical axis of light on the optical path 109 and the end surface S are set by about 60 °_inThe angle formed between, and the optical axis and end surface S of the light on the optical path 111_outEach of the angles formed therebetween, the end surface S can be reduced_inAnd S_outReflection loss in the optical waveguide.

(eighteenth embodiment)

Fig. 20 is a diagram showing an eighteenth embodiment, which is a specific example of the optical device in fig. 11A to 11E.

The eighteenth embodiment is an example of a case where the first reflecting surface 101 and the second reflecting surface 102 are not parallel to each other. Here, although the first and second reflection surfaces 101 and 102 are described as being non-parallel, the first and second reflection surfaces 101 and 102 must face each other. That is, in this arrangement, light from the first reflective surface 101 may be reflected by the second reflective surface 102.

For example, the angle α formed between the first reflective surfaces 101(1016 'and 1017') and the second reflective surfaces 102(1026 'and 1027') is about 60 °. the first reflective surface 1016 'and the second reflective surface 1026' correspond to the case where the rotation angle θ is 56 °, and the first reflective surface 1017 'and the second reflective surface 1027' correspond to the case where the rotation angle θ is 63 °.

R1 is the length of a vertical line drawn from the rotation axis 104 to the first reflection surface 101 or a plane including the first reflection surface 101, and R2 is the length of a vertical line drawn from the rotation axis 104 to the second reflection surface 102 or a plane including the second reflection surface 102. In this case, the coordinates (x) of the intersection 105₀₁,y₀₁) And the coordinates (x) of the intersection 106₀₂,y₀₂) The following formulae (51) to (54) are given.

...(51)

...(52)

...(53)

...(54)

When (x)₁,y₁) Is a coordinate on the first reflecting surface 101 and (x)₂,y₂) Are coordinates on the second reflecting surface 102, these coordinates are described in the following equations (55) and (56).

y₁-y₀₁＝(tanθ)×(x₁-x₀₁)

...(55)

y₂-y₀₂＝(tan(θ+α))×(x₂-x₀₂)

...(56)

Here, (x)_m1，y_m1) Is the point at which light from the non-collimating optical system 400 is reflected by the first reflective surface 101, and (x)_m2，y_m2) Is the point at which light is reflected by the second reflective surface 102. In addition, y_BIIs the y coordinate on optical path 109, and (x)_BR，y_BR) Is a coordinate on the optical path 110 between the first reflective surface 101 and the second reflective surface 102. In this case, the coordinates on the optical path 110 between the first reflecting surface 101 and the second reflecting surface 102 can be described in equation (57).

y_BR-y_m1＝tan(2θ)×(x_BR-x_m1)

...(57)

In addition, (x)_o，y_o) Is the coordinate on the optical path 111 between the second reflecting surface 102 and the third reflecting surface 114, the coordinate on the optical path 111 can be described in equation (58).

y_o-y_m2＝tan(2α)×(x_O-x_m2)

...(58)

As understood from the above, the amount of movement of the exit position does not depend on the distances R1 and R2 between the rotation axis 104 and the first and second reflection surfaces 101 and 102, but depends on the distance (R1+ R2) between the first and second reflection surfaces 101 and 102. That is, when the distance between the first reflection surface 101 and the second reflection surface 102 is shortened, the amount of movement of the exit position can be reduced. In contrast, when the distance between the first reflection surface 101 and the second reflection surface 102 is lengthened, the amount of movement of the exit position can be increased.

In the foregoing configuration, for example, collimated light (parallel light) is incident on a condenser lens 117 'having a focal length of 100mm, a rotation angle θ of the stage 103 is controlled in a range of 56 ° to 63 °, the first reflection surface 101 is disposed at a position 50mm (R1 ═ 50) from the rotation axis (104), and the second reflection surface 102 is disposed at a position 0mm (R2 ═ 0) from the rotation axis (104), the second reflection surface 102 is inclined α ═ 60 ° with respect to the first reflection surface 101, and the lens 117' is disposed at a position 300mm in the x direction and-25.7 mm in the y direction from the rotation axis 104.

In the foregoing configuration, the moving amount of the outgoing light emitted from the focus position shifter can be realized to be 10.5 mm. That is, by controlling the rotation angle θ of the stage 103, the focus position in the direction perpendicular to the optical axis can be controlled within a range of 10.5mm from 0mm (reference point). Furthermore, from each point of emergence (x)_i,y_i) The emitted lights are parallel to each other. Thus, when going from each point of departure (x)_i,y_i) When the beam diameter of the emitted light is constant at the focal point and the focal position shifter is used in the processing device, improvement in processing accuracy and the like can be achieved.

(nineteenth embodiment)

Fig. 21 is a diagram showing a nineteenth embodiment, which is a specific example of the optical apparatus in fig. 11A to 11E.

The nineteenth embodiment is an example in which a third reflecting surface 1146 that returns light from the second reflecting surface 102 to the second reflecting surface 102 is further provided in the fifteenth embodiment described above. In this case, the light from the incident point 112 is reflected by the third reflective surface 1146 and returns along substantially the same path to propagate to the exit point 112'. That is, the incident point 112 and the exit point 112' of the light are located at substantially the same position.

As in the fifteenth embodiment described above, the third reflecting surface 1146 is, for example, a mirror having two perpendicular reflecting surfaces. Here, in this example, the direction in which the light is displaced by the third reflection surface 1146 is a direction perpendicular to the upper surface of the stage 103. Accordingly, the optical paths of the incident light incident on the third reflection surface 1146 and the reflected light reflected by the third reflection surface 1146 may be shifted.

Thus, when the light is returned only once using the third reflection surface 1146, the amount of movement of the exit position is almost doubled. When the moving amount of the exit position is constant, in this example, the range of the rotation angle θ of the stage 103 can be set small, and the load on the current motor can be reduced. That is, in this example, as in the fourteenth embodiment, since the emission position can be moved by a required movement amount according to a small rotation angle θ, the focus position can be controlled at high speed and with high accuracy.

In this example, when the direction in which light travels toward the third reflective surface 1146 is set as a forward path and the direction in which light returns from the third reflective surface 1146 is set as a return path, the light may reciprocate a plurality of times along the forward path and the return path. In this case, a new reflection surface of the return light may also be provided on the incident point 112 side.

In the fifteenth embodiment, the direction in which the light is displaced by the third reflective surface 1144 is a direction parallel to the upper surface of the stage 103. In this case, when viewed on the lateral side of the stage 103, the light traveling toward the third reflection surface 1144 and the light returning from the third reflection surface 1144 overlap each other, and when viewed on the upper side of the stage 103, the light traveling toward the third reflection surface 1144 and the light returning from the third reflection surface 1144 do not overlap each other.

However, in the case of the nineteenth embodiment, the direction in which light is displaced by the third reflection surface 1146 is a direction perpendicular to the upper surface of the stage 103. In this case, when viewed on the lateral side of the stage 103, the light traveling toward the third reflection surface 1146 and the light returning from the third reflection surface 1146 do not overlap with each other, and when viewed on the upper side of the stage 103, the light traveling toward the third reflection surface 1146 and the light returning from the third reflection surface 1146 overlap with each other.

Here, the fifteenth embodiment and the nineteenth embodiment may also be combined. That is, the direction in which the light is displaced by the third reflection surface may be an oblique direction that is not parallel or perpendicular to the upper surface of the stage 103. In this case, when viewed on the lateral side of the stage 103, the light traveling toward the third reflection surface 1144 and the light returning from the third reflection surface 1146 do not overlap with each other, and when viewed on the upper side of the stage 103, the light traveling toward the third reflection surface 1146 and the light returning from the third reflection surface 1144 do not overlap with each other.

(other embodiments)

The embodiments of the present invention have been described, but the present invention is not limited to the embodiments and can be modified in various forms within the scope of the gist of the present invention.

For example, in a processing apparatus that performs work such as marking, punching, or welding using a laser, it is important to control the focal position of light from a laser oscillator at high speed and with high accuracy. The above-described focus position shifter may be applied to such a processing apparatus.

Fig. 22 shows an example of a processing device.

The processing apparatus includes a light source 300, a non-collimating optical system 400 on which light from the light source 300 is incident, and a

focus position shifter

100 or 200 that controls an optical path length of the light from the non-collimating optical system 400. An article 901 to be processed is set on the stage 900. By controlling the focal position of light on article 901, work such as marking, punching, or welding can be performed on article 901.

Further, the microscope may be configured using the above-described focus position shifter. In this case, when the planar direction of the measurement target is the x-y direction and the depth direction thereof is the z direction, the focal point can be scanned at high speed on a specific x-z plane. For example, in a multiphoton microscope, a fluorescence microscope, or the like, a nonlinear effect, absorption of a fluorescent material, or the like occurs depending on a focal position of light emitted to a measurement target. Therefore, by acquiring information at the focal position, three-dimensional imaging can be performed.

Up to now, imaging is performed by scanning radiation light in a planar direction (x-y direction) toward a measurement target, then changing a depth direction (z direction), and scanning the radiation light onto a plane at that position. However, in this embodiment, since imaging can be performed at high speed in the depth direction, movement or the like of a substance from the surface of the measurement target in the depth direction can be observed.

The inspection apparatus may be configured using the focus position mover described above.

For example, in an inspection apparatus that inspects a surface state of an object, it is necessary to radiate radiation light at a constant radiation angle to avoid a change in beam diameter at the angle of the radiation light.

However, since the inspection apparatus in the related art controls the focal position in the direction perpendicular to the optical axis using the f- θ lens, the beam diameter at the focal point may inevitably vary. Therefore, when the above-described focus position mover is used in such an inspection apparatus, the focus position in the direction perpendicular to the optical axis can be controlled without changing the beam diameter at the focus.

In each of the embodiments described above, it is important that the first reflecting surface 101 and the second reflecting surface 102 are rotated about the rotational axis 104 in a state where the relative arrangement between the first reflecting surface 101 and the second reflecting surface 102 is maintained. Therefore, in this example, the stage 103 is provided, and the first reflection surface 101 and the second reflection surface 102 facing each other are fixed to the stage 103.

However, for example, according to a method in which the stage 103 is not used, the first reflecting surface 101 and the second reflecting surface 102 can be rotated about the rotational axis 104 in a state in which the relative arrangement between the first reflecting surface 101 and the second reflecting surface 102 is maintained. For example, a first motor driving the first reflecting surface 101 and a second motor driving the second reflecting surface 102 may be provided. Here, in this case, the control unit 120 must control the rotation in a state where the first motor and the second motor are synchronized.

The control of the focal position in the direction perpendicular to the optical axis may be applied to a technique for moving the optical path of light in the direction perpendicular to the optical path (i.e., controlling the exit position of light in that direction). That is, for an optical apparatus that does not include the non-collimating optical system 400 or an optical apparatus that includes the non-collimating optical system 400 but does not control the exit position to control the focal position, the above-described embodiments can be applied as an optical apparatus that merely moves the optical axis of light.

According to the foregoing embodiments, an optical apparatus advantageous to control the focal position of light at high speed and with high accuracy can be realized. That is, the focal position can be controlled at high speed and with high accuracy in the optical axis direction without moving the condenser lens. In addition, the focal position in the direction perpendicular to the optical axis can be controlled at high speed and with high accuracy without changing the beam diameter at the focal position.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of japanese patent application No. 2018-172135, filed on 9/14/2018, which is hereby incorporated by reference in its entirety.

Claims

1. An optical device for controlling a focal position of light, comprising:

a first reflective surface configured to be rotatable about a rotation axis and to reflect light;

a second reflecting surface configured to be rotatable about the rotation axis, face the first reflecting surface, and reflect light from the first reflecting surface;

a third reflective surface that returns light from the second reflective surface to the second reflective surface; and

a control unit configured to: the focal position in the optical axis direction of light returned from the third reflection surface to the first reflection surface via the second reflection surface is controlled by rotating the first reflection surface and the second reflection surface around the rotation axis in a state where the relative arrangement between the first reflection surface and the second reflection surface is maintained.

2. An optical device for controlling a focal position of light, comprising:

a second reflecting surface configured to be rotatable about the rotation axis, face the first reflecting surface, and reflect light from the first reflecting surface; and

a control unit configured to: the focal position of the light from the second reflecting surface in the direction perpendicular to the optical path is controlled by rotating the first reflecting surface and the second reflecting surface about the rotating axis in a state where the relative arrangement between the first reflecting surface and the second reflecting surface is maintained.

3. The optical device of claim 1, further comprising:

a gantry configured to be rotatable about the rotation axis,

wherein the first reflecting surface and the second reflecting surface are fixed on the stage, and

wherein the control unit controls the focus position by changing a rotation angle of the stage.

4. The optical device of claim 1, wherein the axis of rotation is located in a region between the first and second reflective surfaces.

5. The optical device of claim 1, wherein the axis of rotation is located in a region other than a region between the first and second reflective surfaces.

6. The optical device of claim 1, wherein a size of the first reflective surface is different from a size of the second reflective surface.

7. The optical device of claim 1, wherein a length of a perpendicular line drawn from the axis of rotation to the first reflective surface or a plane including the first reflective surface is different from a length of a perpendicular line drawn from the axis of rotation to the second reflective surface or a plane including the second reflective surface.

8. The optical device of claim 1, wherein the first and second reflective surfaces are not disposed point-symmetrically with respect to the axis of rotation.

9. The optical device of claim 1, wherein the light reciprocates a plurality of times between the first reflective surface and the second reflective surface.

10. The optical device of claim 1, wherein the third reflective surface reflects the reflected light to the same optical path as the incident light.

11. The optical device of claim 1, further comprising:

a fourth reflecting surface configured to extract light returned from the third reflecting surface to the first reflecting surface via the second reflecting surface.

12. The optical device of claim 11, further comprising:

a fifth reflecting surface configured to return light returned by the third reflecting surface and reflected by the first reflecting surface to the first reflecting surface,

wherein the third reflection surface and the fifth reflection surface reflect the reflected light to an optical path different from an optical path of the incident light, and

wherein the fourth reflecting surface extracts light returned from the fifth reflecting surface to the second reflecting surface via the first reflecting surface.

13. The optical device of claim 1, wherein the light is changed into converging or diverging light by the non-collimating optical system before being reflected by the first reflecting surface.

14. The optical device of claim 2, wherein the light is changed into converging light by the non-collimating optical system after being reflected by the first and second reflective surfaces.

15. The optical device of claim 1, wherein the first reflective surface and the second reflective surface are non-parallel.

16. The optical device of claim 1, wherein the second reflective surface is disposed closer to the axis of rotation than the first reflective surface.

17. The optical apparatus according to claim 1, wherein the control unit drives the first and second reflective surfaces using a current motor.

18. The optical apparatus according to claim 1, wherein the control unit drives the first and second reflecting surfaces using a rotary motor capable of unidirectional rotation.

19. An optical device for controlling a focal position of light, comprising:

a control unit configured to: the optical path of the light from the second reflecting surface is moved in a direction perpendicular to the optical path by rotating the first reflecting surface and the second reflecting surface about the rotation axis in a state where the relative arrangement between the first reflecting surface and the second reflecting surface is maintained.

20. A processing apparatus, comprising:

an optical device according to one of claims 1, 2 and 19; and

a light source configured to generate light incident on the optical device,

wherein the item disposed at the focal position is processed by controlling the focal position.